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Re: In the above figure, if PQRS is a square, PT is perpendicular to QT
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26 Nov 2017, 08:16

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amanvermagmatYour approach to this question is not perfect, actually, the square in this question is not placed symmetrically wrt axes. Hence the diagonal is not perpendicular to PT. See the attachment. So RPT is not right-angled triangle . So further explanation is fallacious. the right solution has been posted and the answer is C .

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amanvermagmat wrote:

In right angled triangle PTQ, we can get PQ = 5. Thus all sides of this square are 5, which means diagonals of this square = PR = QS = 5√2.

Now, lets just join PR. PRT is another right angled triangle right angled at P. And RT is the hypotenuese of this triangle. So, by pytahgoras theorem, RT = √(5√2)^2+(4)^2 = √66

join R with T and R with y axis as shown in figure attached..the sides of square are \(\sqrt{3^3+4^2}=5\)so triangles PQT and ARQ will be similar triangles.. HYP =5 and angles are 90, x and 90-xso AR = 3 and AQ = 4..

Re: In the above figure, if PQRS is a square, PT is perpendicular to QT
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26 Nov 2017, 09:51

Janvisahu wrote:

amanvermagmatYour approach to this question is not perfect, actually, the square in this question is not placed symmetrically wrt axes. Hence the diagonal is not perpendicular to PT. See the attachment. So RPT is not right-angled triangle . So further explanation is fallacious. the right solution has been posted and the answer is C .

Give Kudos , if you like my post .

amanvermagmat wrote:

In right angled triangle PTQ, we can get PQ = 5. Thus all sides of this square are 5, which means diagonals of this square = PR = QS = 5√2.

Now, lets just join PR. PRT is another right angled triangle right angled at P. And RT is the hypotenuese of this triangle. So, by pytahgoras theorem, RT = √(5√2)^2+(4)^2 = √66

Hence E answer

Hi

Thanks for bringing it to my attention. I have deleted that post in the light of this new knowledge.

join R with T and R with y axis as shown in figure attached..the sides of square are \(\sqrt{3^3+4^2}=5\)so triangles PQT and ARQ will be similar triangles.. HYP =5 and angles are 90, x and 90-xso AR = 3 and AQ = 4..

join R with T and R with y axis as shown in figure attached..the sides of square are \(\sqrt{3^3+4^2}=5\)so triangles PQT and ARQ will be similar triangles.. HYP =5 and angles are 90, x and 90-xso AR = 3 and AQ = 4..

The figure it not drawn accurately and thus causes confusion. PT = 4 and TQ = 3, but they both look like they equal 4. Because of this, it seems like the square is just turned 45 degrees and you can draw a perpendicular line down from PT to PR - which is in fact, not the case. If you were to create an accurate drawing the line would be skewed.

We see that triangle QPT is a 3-4-5 right triangle; thus PQ = 5. The way the figure is drawn, we are being tricked into thinking that the diagonal of the square is perpendicular to the line PT, but we should notice that that would happen only when the angle TPQ is 45 degrees, which is not the case since the triangle PTQ is not isosceles.

Instead, draw segments RT and drop a perpendicular from R into line QT. Let’s say the perpendicular meets the line QT at the point W. Now, we have a right triangle where the hypotenuse is RT and the legs are RW and TW. Since the triangle PTQ is similar to the triangle RQW (notice that the angle PQT is equal to the angle QRW), the length of the segment QW will be 4 and the length of the segment RW will be 3. Now, the two legs of the right triangle RTW are 3 and 3 + 4 = 7, and the hypotenuse of RTW, which is RT, can be found using the Pythagorean Theorem: |RT|^2 = 3^2 + 7^2 = 9 + 49 = 58; thus RT = √58.